JPS5822494B2 - Method for producing europium-activated tin oxide phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a europium-activated tin oxide phosphor, and aims to provide a method for producing a brighter tin oxide-based phosphor.

This phosphor emits red-orange light, unlike the bluish-green light emitted by ZnO:Zn, the only conventionally known phosphor for low-speed electron beams.

Its typical emission spectrum is shown in FIG.

By using this phosphor, character display tubes can be made multicolored, and are extremely useful for digital displays in various devices that have become popular in recent years.

Furthermore, this phosphor has the possibility of realizing a flat color display.

In order to give this europium-activated tin oxide SnO2:Eu phosphor more practical value, the present invention devises a manufacturing method and improves its brightness.

Conventionally, 5n02: Eu phosphor was produced by adding aqueous ammonia to a mixed aqueous solution of tin chloride and europium chloride until the pH reached 8.5 to obtain a hydroxide coprecipitate, which was then dried and then heat-treated. It is obtained by

C hydroxide precipitates have a small particle size of 0.01 μm and are difficult to handle in production, and have the disadvantage that they easily change to 5n02 during drying and tend to lose reaction activity during subsequent heat treatment. However, the brightness of the final phosphor was still insufficient.

In addition, a method of creating an oxalate coprecipitate and thermally decomposing it has also been practiced, but the resulting particles tend to become dendritic and exhibit a blow-up phenomenon during thermal decomposition, resulting in The particle size of the photon particles was also difficult to reach 1.5 μm or more, and the brightness was also insufficient as in the above-mentioned method.

The present invention uses at least one of metal tin, tin halide, and tin sulfate as a starting material, and adds nitric acid to a mixture of this starting material and europium, and evaporates to dryness while stirring with heating. By preparing metastannic acid powder and heat-treating this powder, a brighter 5n02:Eu phosphor could be obtained by decomposing metastannic acid and diffusing europium into the oxidized matrix. It is something.

Hereinafter, the present invention will be specifically explained using examples.

Example 1 High purity metal tin and europium oxide Eu2 as starting materials
Prepare O3 and mix it with 47.5 grams of tin in various proportions so that Eu is I x 10-'' to 15 atomic % with respect to Sn, put each mixture into a quartz beaker, and add C. Furthermore, 250 cc of high-purity nitric acid for the electronic industry diluted with pure water was added.

Each was stirred while heating on a magnetic mixer equipped with a hot plate to form and precipitate metastannic acid, and then they were finally evaporated to dryness.

Transfer the precipitated powder to an alumina crucible with a lid,
Heat treatment was performed at a temperature within the range of 0 to 1500°C for 2 to 10 hours.

Example 2 A phosphor was prepared in the same manner as in Example 1 using 90.3 grams of high purity tin chloride 5nC1□.2 H2O and 2030.70 grams of Eu as starting materials.

Example 3 High purity tin bromide 5nBr2111.4 grams and Eu203
Using 0.70 grams as a starting material, a phosphor was produced under the same conditions as in Example 1.

Example 4 High purity tin sulfate S n SO485, 9 grams and E u
Using 2030.7 grams as starting material, Example 1
A phosphor was made under the same conditions.

The phosphor powder obtained in the above example was caused to emit light using a low-speed electron beam excitation device having a structure as shown in FIG.

In the figure, reference numeral 1 denotes a glass plate having a transparent electrode 2, and a fluorescent film 3 is coated on the side of the transparent electrode 2 at a rate of 3 cyrt/cyrt.

A mica plate 4 having an opening of 5 mm x 5 mm is placed in front of the fluorescent film 3, and a grid 5 is attached in front of the mica plate 4.

This grid 5 has a honeycomb-like structure as shown in FIG.

6 is a thermionic emission heater. All of these components were assembled into a glass vacuum container γ.

Ef represents the filament voltage, Eo represents the grid voltage, and Eb represents the anode voltage.

Ef=3. OV, Eo = 18V, change Eb,
Brightness was measured using a photometer.

The brightness of each phosphor was compared at a value of Eb=10v.

The table below summarizes the brightness of the phosphors obtained in the Examples when Eb=10V and the characteristics of the phosphor particles or precipitated particles.

As is clear from the results of samples 1 to 6 in the table above, when the heat treatment conditions were constant at 1300°C for 2 hours, Eu
When the concentration is between 0-2 and 15 atomic percent, it emits bright red-orange light.

The 5n02:Eu phosphor obtained up to now has a maximum brightness of 16 foot lamberts, and all exhibit brightness that exceeds this.

In particular, when Eu is 5 x 10-2 to 10 atomic %, it exhibits a brightness of 25 feet Lambert.

Samples 10 to 12 show that good results can be obtained using tin halides and sulfates as the starting material for tin.

Of course, a mixture of two or more of these compounds or metal tin can also be used as the starting material.

Regarding the heat treatment conditions, Sample No. 6, No. 9-12, and No. 7
, 8, it can be seen that the heat treatment temperature is 1.
When the temperature is around 200°C, the brightness is not so good compared to a phosphor heat-treated at a temperature of 1300°C or higher.

Of course, by increasing the heat treatment time as in sample 8, the brightness can be improved.

When carried out industrially, it is more practical to set the heat treatment temperature to 1300°C or higher.

Needless to say, at this time, the temperature must be within a temperature range in which tin oxide does not melt.

Furthermore, it was confirmed that the same effect could be obtained by using a stannic halide or sulfate instead of the stannous halide or sulfate as in the above examples.

As described above, according to the method of the present invention, 5n02:
Not only can the brightness of the Eu phosphor be improved, but its manufacture is also very easy.

The phosphor obtained by the method of the present invention also has a particle size of 5nQ2:Eu phosphor obtained by the conventional method.
The particle size is larger than that of about 5 μm, making it easier to handle.

[Brief explanation of the drawing]

Figure 1 shows 5n02 obtained by the manufacturing method of the present invention:
FIG. 2 is an electron beam emission spectrum diagram of an Eu phosphor. FIG. 2 is a schematic diagram of a low-speed electron beam excitation device that is one of the application examples of fluorescent powder, and FIG. 3 is a diagram showing the structure of its control grid.

Claims (1)

[Scope of Claims] 1. At least one of metal tin, a tin halide, and tin sulfate is used as a starting material, and d. europium is contained in a proportion of I x 10-2 to 15 atomic % relative to tin. nitric acid is added to this mixture and evaporated to dryness while heating and stirring to produce metastannic acid powder, which is then heat treated to cause decomposition and diffusion of europium into the tin oxide matrix. A method for producing a featured europium-activated tin oxide phosphor. 2. Using at least one of metal tin, a tin halide, and tin sulfate as a starting material, europium is mixed with this starting material at a ratio of 5 x 10'' to 10 atomic percent relative to tin, and nitric acid is added to this mixture. In addition, metastannic acid powder is produced by evaporation to dryness while heating and stirring, and this is heat-treated to cause decomposition and diffusion of europium into the tin oxide matrix. The method for producing a europium-activated tin oxide phosphor according to claim 1. 3. The heat treatment temperature of the metastannic acid powder is 1200° C. or higher, which is within a temperature range at which tin oxide does not melt. A method for producing a europium-activated tin oxide phosphor according to item 1 or 2.